A vehicle side portion structure, which includes a door beam provided within a front side door in a front-rear direction of a vehicle body with a rear-end section being supported by a box-shaped bracket, and a bulkhead (separator member) provided within the box-shaped bracket member, is known from, for example, Patent Literature 1, JP-A 2008-13139.
In the above-described vehicle side portion structure, when an impact load is inputted into the front side door from sideward of the vehicle, the rear end of the door beam is brought into abutment against the bulkhead to thereby disperse the impact load to the vehicle body.
However, in the structure disclosed in Patent Literature 1, it is anticipated that the impact load inputted into the front side door from sideward of the vehicle will deform the front side door to cause the rear end section of the door beam and the bulkhead to move upward. As the door beam rear end and the bulkhead are moved upward, the bracket member and the bulkhead will likely be separated from their respective support portions on the vehicle body, in which instance the support sections can hardly support the bracket and the bulkhead.
Hence, it becomes difficult for an impact load inputted from sideward of the vehicle to the front side door to be suitably born by the vehicle body by causing the impact load to be transmitted through the door beam and bulkhead to the vehicle body. Thus, there is a fear that the door beam and the bulkhead (i.e., front side door) will stick out into a vehicle compartment. Therefore, there has been a demand for a measure to remove the fear.